Capillary tube/plate refrigerant/air heat exchanger for use in conjunction with a method and apparatus for inhibiting ice accumulation in HVAC systems

ABSTRACT

A non-stick coating, which inhibits frozen moisture accumulation, is applied to the exterior exposed portions of a refrigerant/air heat exchanger, which heat exchanger is comprised of a capillary tube/plate means/design, which plate has an exterior surface that is comprised of at least one of raised dots, ridges, trenches, and a flat surface, which means/design facilitates the shedding of frozen moisture and maximizes heat exchanger surface area exposure to the air; for use in conjunction with an air source heat pump system, an evaporative cooling system or a chiller, or as a supplement to a water-source heat pump system or to a direct expansion heat pump system; and for use with any other refrigerant-based heating system or cooling system.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a Continuation-In-Part application which claims benefit of co-pending U.S. patent application Ser. No. 10/073,515 filed Feb. 11, 2002, entitled “Method and Apparatus for Inhibiting Ice Accumulation in HVAC Systems” which is hereby incorporated by reference.

A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SEQUENCE LISTING OR COMPUTER PROGRAM LISTING APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

This invention relates to the field of refrigerant-based heating and cooling systems, and to evaporative cooling systems, and more particularly to a system designed to inhibit condensation or other frozen moisture accumulation on heat exchange equipment or tubing, which tubing is typically finned, and which equipment or tubing is exposed to the air, by means of the application of a non-stick coating to the exterior portion of such air-exposed equipment or tubing, or finned tubing, or the like.

Virtually all heating and cooling systems utilize equipment or a heat exchange means which periodically is exposed to air containing moisture, or water vapor. For example, well-known air source heat pump systems typically utilize exterior heat exchange units consisting of finned copper tubing, which tubing transports a refrigerant such as R-22, R-410A, or the like, with an electric fan utilized to blow air over the finned tubing to accelerate heat transfer from the warm air to the cold refrigerant fluid in the heating mode, and from the hot refrigerant fluid to the cool air in the cooling mode. Such a system also typically incorporates an interior air heat exchange unit comprised of finned copper tubing and an electric fan, a compressor which is used to both compress the refrigerant vapor and to circulate the refrigerant fluid through the system, an expansion valve, and other miscellaneous parts and optional apparatus, well known in the field, depending on the particular design.

While copper is generally utilized for heat transfer tubing in most common refrigerant-based systems applications, other materials, such as titanium or the like, may also be utilized for the refrigerant/air heat transfer tubing and/or plates, just as various other system components may vary. Also, in large commercial chillers, plastic tubing is commonly utilized to transport water for evaporative cooling purposes, which water has typically been heated from waste heat augmented by heat of compression from a refrigerant-based heat transfer system.

However, when typical air-source heat pump systems are operating in the heating mode, since the refrigerant fluid, which is being circulated into the exterior outdoor heat exchange unit exposed to the air, is typically below the freezing point of water, as the exterior air temperature approaches, or falls below, the freezing point of water, humidity in the air collects on the finned tubing and is frozen. This freezing humidity gradually builds up ice accumulations to the extent that it blocks the airflow designed to pass over the finned tubing, thereby rendering the system unable to acquire sufficient heat from the air to operate at design levels. Consequently, a defrost cycle is commonly utilized to remove the ice when the accumulation becomes excessive. The defrost cycle for a residential air source heat pump system typically lasts for about eight minutes, and actually consists of operating the heat pump system in the cooling mode, so as to run hot refrigerant fluid through the exterior finned tubing to melt the ice. As the heat pump system is operating in the cooling mode during the defrost cycle, heat is being taken from the interior air via the interior heat exchange unit, which heat is typically replaced via electric resistance heat or via a fossil fuel means. This periodic defrost cycle results in excessive wear and tear on the compressor, tending to shorten compressor life, as well as in lowered system efficiencies and higher operational costs.

There have been many attempts to make the defrost cycle more efficient, such as using more efficient equipment designs, using stored energy to heat the refrigerant fluid used in the defrost cycle, and the like. However, there remains a need to provide a means to eliminate the necessity for a defrost cycle in an air source heat pump system, and to eliminate unwanted ice accumulations, whether from condensation ice, freezing rain, snow, or hail, on the exterior portion of any refrigerant-based heat transfer system part, whether commercial or residential, resulting from an accumulation of frozen moisture.

Similarly, in large commercial evaporative cooling chillers, which must periodically operate in below freezing temperatures, and which sometimes must operate with a cooling load significantly less than called for by system design, the water utilized for evaporative cooling on the exterior of the heat transfer tubing may freeze. Consequently, under such conditions, there is a similar need to provide an efficient means to eliminate the necessity for a costly de-icing operation.

In Wiggs' U.S. patent application Ser. No. 10/073,515, entitled “Method and Apparatus for Inhibiting Ice Accumulation in HVAC Systems,” a new and useful method and apparatus was taught to prevent ice buildup on HVAC refrigerant/air heat exchange surfaces via coating the surfaces with a non-stick coating to which ice/frozen moisture would not adhere. While certain examples of suitable refrigerant/air heat exchange means were shown, the present invention discloses another, and potentially better, example of a refrigerant/air heat exchanger means/design which could alternatively be utilized.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an alternative, and potentially better, example of a refrigerant/air heat exchanger means/design which could alternatively be utilized to inhibit ice accumulations on system component areas of any refrigerant-based heat transfer system or evaporative cooling system where accumulated frozen moisture, such as frozen humidity, frozen rain, snow, or hail, would decrease system operational design efficiencies for any reason.

This objective is accomplished by a system/method means of applying a non-stick coating to the exterior portion of any refrigerant-based and/or evaporative cooling based heating or cooling system where undesirable ice accumulation could occur, where the exterior portion of the refrigerant/air heat exchanger is comprised of a capillary tube/plate means/design. In this design, refrigerant transport capillary tubes are situated with at least one metal, or the like, plate. The construction of the at least one plate would typically be comprised of a metal, such as copper or the like, but could be comprised of any material that had an acceptably sufficient heat transfer rate. The plate could be in any form, such as square, rectangular, round, or the like, as would be well understood by those skilled in the art. The capillary tubes evenly distribute the heat transport refrigerant within and throughout the at least one plate, which plate has a very large air surface exposure area, so as to facilitate refrigerant/air heat transfer. The capillary tubes could be comprised of separate small refrigerant transport tubes positioned within the at least one plate, which plate would be comprised of a separate material from the copper, or the like, capillary tubes. In the alternative, for example, the capillary tubes could be comprised of small refrigerant transport holes/passageways within the at least plate itself, such as a plate of copper with a honeycomb of small refrigerant transport passageways drilled and/or formed throughout the plate itself.

As with the former invention disclosed by Wiggs in the aforesaid U.S. patent application Ser. No. 10/073,515, the operation of an electric fan, with or without a vibrator, may blow away any thin film of humidity induced condensation ice, or other form of frozen water, which has not fallen by operation of gravity, from the non-stick exterior surface of such a heat exchange capillary tube/plate means/design of a conventional air-source, or other, heat pump system.

The at least one plate may have at least one of an exterior flat surface, a dotted surface, a rippled surface, a trenched surface, or the like, so as to increase surface area exposure to the air. The at least one plate should be at least one of vertically positioned and downwardly sloped in a manner so as to facilitate the fall of any accumulated frozen moisture off of the at least one plate via gravity alone, as opposed to being horizontally positioned where ice could remain on the top. The at least one plate would typically have at least one refrigerant transport supply line and at least one refrigerant transport discharge line to/from the refrigerant transport capillary tubing within the plate.

The exterior non-stick coated capillary tube/plate refrigerant/air heat exchanger unit can be used with or without an electric fan, with or without a vibrator, and with or without a protective shell, as previously disclosed in the aforesaid Wiggs' U.S. patent application Ser. No. 10/073,515.

The exterior non-stick coated capillary tube/plate refrigerant/air heat exchanger unit can be used with an air-to-air heat pump system, can be used as a supplement to an open loop or a closed loop water-source heat pump system, can be used as a supplement to a direct expansion heat pump system such as those described in U.S. Pat. Nos. 5,623,986 and 5,946,928 to Wiggs, for example, can be used in a commercial evaporative cooling system, or can be used in any other application apparent to those skilled in the art/trade. As would also be well understood by those skilled in the art, the at least one capillary tube/plate refrigerant/air heat exchanger could be duplicated and utilized in at least one of a series and a parallel heat exchange application for larger sized systems.

In a heat exchange system such as an air-source heat pump system/method, an open loop or closed loop water-source heat pump system, a direct expansion heat pump system, or an evaporative cooling system, the heat exchange system/method would have at least one heat exchange component comprised of at least one heat exchange surface plate, which plate would contain at least one of refrigerant transport tubing and refrigerant transport passageways, and would have a non-stick coating applied to the exterior of the at least one heat exchange surface plate, with such heat exchange surface plate component being oriented to promote gravity flow of frozen moisture away from the at least one heat exchange component.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

There are shown in the drawings embodiments of the invention as presently preferred. It should be understood, however, that the invention is not limited to the exemplary arrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 is a side view of a vertically oriented capillary tube/plate refrigerant/air heat exchanger, which plate contains refrigerant transport capillary tubes situated within the plate and between at least one refrigerant entry/supply line and at least one refrigerant discharge line, and where the exterior of the plate has been coated with a non-stick exterior coating.

FIG. 2 is a front view of a downwardly sloped capillary tube/plate refrigerant/air heat exchanger, together with a front view of refrigerant entering/supply line.

FIG. 3 is a top view of a vertically sloped capillary tube/plate refrigerant/air heat exchanger, with a flat plate exterior side, together with a top view of refrigerant entering/supply line and a refrigerant discharge line.

FIG. 4 is a front view of the surface of a plate, with an extended/raised dot exterior side, which surface is dotted with small extended/raised dots so as to increase air exposure surface area, together with a front view of refrigerant entering/supply line.

FIG. 5 is front view of the surface of a plate, which exterior side surface is rippled with small ridges so as to increase air exposure surface area, together with a front view of refrigerant entering/supply line.

FIG. 6 is a top view of a vertically sloped capillary tube/plate refrigerant/air heat exchanger, with the exterior sides of the plate embedded with trenches so as to increase air exposure surface area, together with a top view of refrigerant entering/supply line and a refrigerant discharge line.

DETAILED DESCRIPTION OF THE INVENTION

A method and apparatus for inhibiting condensation ice accumulation on heat transfer systems, including refrigerant-based heating and cooling systems, and on an evaporative cooling system, according to the invention, utilizes a non-stick coating applied to capillary tube/plate means/design heat exchange components where ice accumulation is not desirable because such ice decreases overall system operational efficiencies.

The following detailed description is of the best presently contemplated mode of carrying out the invention. The description is not intended in a limiting sense, and is made solely for the purpose of illustrating the general principles of the invention. The various features and advantages of the present invention may be more readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings.

Referring now to the drawings in detail, where like numerals refer to like parts or elements, there is shown in FIG. 1 a cut-away side view of a vertically sloped/oriented 14 capillary tube/plate refrigerant/air heat exchanger 1. The plate 2 contains refrigerant transport capillary tubes 3 situated within the plate 2 and between at least one refrigerant entry/supply line 4 and at least one refrigerant discharge line 5, and where the exterior 6 surface 8 of the plate 2 has been coated with a non-stick exterior coating 7. (As would be well understood by those skilled in the art, the refrigerant supply line 4 and discharge line 5 would serve in opposite capacities if used in the cooling mode, as opposed to the heating mode, of a reverse-cycle heat pump application.) The refrigerant transport capillary tubes 3 may be comprised of at least one of tubing constructed within the plate 2, and of small holes/passageways drilled/formed within the plate 2 itself, as can be readily understood by those skilled in the art. The passageways do not necessarily have to be tubular 3 as shown herein, but could be comprised of square tubing (not shown), triangular tubing (not shown), a space between one side of the plate 2 and the other (not shown), or the like, as would be readily understood by those skilled in the art. As would also be well understood by those skilled in the art, the one capillary tube/plate refrigerant/air heat exchanger 1 shown herein could be duplicated and utilized in conjunction with others in at least one of a series and a parallel heat exchange application.

The non-stick exterior coating 7 may be composed of any substance which will inhibit or prevent ice, or other frozen moisture, from adhering to the exterior 6 surface 8 of the plate 2. When applied to the exterior 6 surface 8 of the plate 2, the substance should be of a type that does not, or does not significantly, impede heat transfer in an insulating fashion. Such a non-stick coating may be composed of a substance such as a tetrafluoroethylene resin (PTFE) Teflon®, such as DuPont Teflon® PFA, having a thickness coating of about 0.003 to 0.004 inches, or such as a fluoropolymer dip coating. Another example of such a non-stick coating may consist of plasma-polymerizing a fluoroethylene monomer, such as tetrafluoroethylene, in the presence of the desired exterior surface and depositing a fluoropolymer coating of about 1/10,000 inch or less on the exterior surface. Another example of such a non-stick coating may be a triazine-dithiol derivative, or the like.

In one embodiment of the system, the capillary tube/plate refrigerant/air heat exchanger 1 shown herein would be incorporated into a direct expansion geothermal heat exchange system. Such systems are known in the art and are shown, for example, in U.S. Pat. Nos. 5,623,986 and 5,946,928, both issued to Wiggs, the disclosures of which are incorporated herein in their entirety. For example, the capillary tube/plate refrigerant/air heat exchanger 1 shown herein can be incorporated into the direct expansion geothermal heat exchange system at a point just before the refrigerant enters the subterranean heat exchanger, with such a subterranean heat exchanger being well understood by those skilled in the art and not shown herein.

FIG. 2 is a front view of a downwardly sloped 13 capillary tube/plate refrigerant/air heat exchanger 1, with a flat plate 12 exterior 6 side, together with a front view of refrigerant entering/supply line 4.

FIG. 3 is a top view of a vertically sloped 14 capillary tube/plate refrigerant/air heat exchanger 1, with a flat plate 12 exterior 6 side, together with a top view of refrigerant entering/supply line 4 and a refrigerant discharge line 5.

FIG. 4 is a front view of the surface 8 of a downwardly sloped 13 plate 2, with an extended/raised dot 9 exterior 6 side, which surface 8 is dotted 9 with small extended/raised dots 9 so as to increase air exposure surface 8 area, together with a front view of refrigerant entering/supply line 4.

FIG. 5 is a front view of the surface 8 of a downwardly sloped 13 plate 2, which exterior 6 side surface 8 is rippled with small ridges 10 so as to increase air exposure surface 8 area, together with a front view of refrigerant entering/supply line 4.

FIG. 6 is a top view of a vertically sloped 14 capillary tube/plate refrigerant/air heat exchanger 1, with the exterior 6 sides of the plate 2 embedded with trenches 11 so as to increase air exposure surface 8 area, together with a top view of refrigerant entering/supply line 4 and a refrigerant discharge line 5. As would be readily understood by those skilled in the art, any plate 2 with a trenched 11 surface 8 would be fitted with trenches 11 that were not horizontally inclined (not shown). A horizontal inclination would obviously prevent frozen moisture (not shown) gravity fall off.

Thus, although there have been described particular embodiments of the present invention of a new and useful Capillary Tube/Plate Refrigerant/Air Heat Exchanger For Use In Conjunction With A Method and Apparatus for Inhibiting Ice Accumulation in HVAC Systems, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims. 

1. A heat transfer system comprising at least one heat exchange component having at least one heat exchange surface plate and a non-stick coating applied to the at least one heat exchange surface plate, the non-stick coating adapted to inhibit adherence of frozen moisture to the at least one heat exchange surface plate.
 2. The heat transfer system of claim 1 wherein the at least one heat exchange surface plate component comprises at least one heat conductive plate, which plate contains at least one of refrigerant fluid transport tubing and refrigerant fluid transport passageways.
 3. The heat exchange surface plate component of claim 2 wherein the surface of the plate is comprised of at least one of raised dots, ridges, trenches, and a flat surface.
 4. The heat transfer system of claim 1 wherein the at least one heat exchange surface plate component is oriented to promote gravity flow of frozen moisture away from the at least one heat exchange component.
 5. In a heat exchange system such as an air-source heat pump system, an open loop or closed loop water-source heat pump system, a direct expansion heat pump system, or an evaporative cooling system, the heat exchange system having at least one heat exchange component comprised of at least one heat exchange surface plate, which plate contains at least one of refrigerant transport tubing and refrigerant transport passageways, and a non-stick coating applied to the exterior of the at least one heat exchange surface plate, with such heat exchange surface plate component being oriented to promote gravity flow of frozen moisture away from the at least one heat exchange component.
 6. A heat transfer method comprising having at least one heat exchange component, which component has at least one heat exchange surface plate, with a non-stick coating applied to the at least one heat exchange surface plate, with the non-stick coating adapted to inhibit adherence of frozen moisture to the at least one heat exchange surface plate.
 7. The heat transfer method of claim 6 wherein the at least one heat exchange surface plate component is comprised of at least one heat conductive plate, which plate contains at least one of refrigerant fluid transport tubing and refrigerant fluid transport passageways.
 8. The heat transfer method of claim 7 comprising at least one heat exchange surface plate wherein the surface of the plate is comprised of at least one of raised dots, ridges, trenches, and a flat surface.
 9. The heat transfer method of claim 6 comprising at least one heat exchange surface plate component that is oriented to promote gravity flow of frozen moisture away from the at least one heat exchange component.
 10. A heat exchange method utilizing an air-source heat pump system, an open loop or closed loop water-source heat pump system, a direct expansion heat pump system, or an evaporative cooling system, comprising a method where the heat exchange system has at least one heat exchange component comprised of at least one heat exchange surface plate, which plate contains at least one of refrigerant transport tubing and refrigerant transport passageways, and a non-stick coating applied to the exterior of the at least one heat exchange surface plate, with such heat exchange surface plate component being oriented to promote gravity flow of frozen moisture away from the at least one heat exchange component. 